The present disclosure relates to an image forming apparatus that recognizes movement of a human body (hereinafter also a “human” or a “user”) by exploiting heat radiated therefrom.
Conventionally, an infrared sensor that detects infrared radiation emanating from a human is commonly used to detect whether or not a human is present within a detection area. For example, results of detecting presence/absence of a human body are used for surveillance and other purposes. For example, a detecting device that uses two sensor units to detect a human body as described below is known.
Specifically, a passive infrared human body detection device is known that is provided with: two sensor units each comprising a light receiving element and an optical system, the first sensor unit being arranged with its light receiving direction pointing to the upper half of the human body to be detected so as to have a detection area that does not reach the ground, the second sensor unit being arranged to have a detection area below that detection area so as to point to the ground at a predetermined detection distance away; two level detection circuits that output detection signals when the output electrical signals from the light receiving elements of the two sensor units exceed predetermined levels; and a human body detection circuit that outputs a human body detection signal when both of the level detection circuits output the detection signals.
When a user wants an image forming apparatus (such as a multifunction product or a copier) to execute a job such as copying or document reading, to make settings and to command execution of the job, the user operates the image forming apparatus.
An infrared sensor may be provided on the image forming apparatus. Whether or not a human is present within the detection area of the infrared sensor may be detected so that results of the detection can be used to manage and control the operation of the image forming apparatus.
For example, when presence of a human is detected within the detection area of the infrared sensor, power saving mode, in which the supply of electric power to particular portions in the image forming apparatus is stopped, can be canceled. Then, the user can make the image forming apparatus execute a job with almost no wait.
However, even in a case like when a human passes by in front of the image forming apparatus, the human enters the detection area of the infrared sensor. In this case, the user approaches the image forming apparatus with no intention to use it; accordingly, there is no need to restart the supply of the electric power to the particular portions (power saving mode should be maintained). However, by conventional detection using an infrared sensor, a human simply passing by (a human simply entering the detection area of the infrared sensor) causes cancellation of the pyroelectric sensor, resulting in unnecessary consumption of electric power.
To eliminate such waste, whether or not a human is approaching the image forming apparatus should be detected accurately. However, by conventional human body detection using an infrared sensor, presence of a human within the detection area of the infrared sensor can be detected, but whether the user is moving toward the image forming apparatus or is simply crossing the detection area is not detected with an accurate distinction. Thus, there is conventionally the problem that the direction of movement of a human with respect to the image forming apparatus cannot be detected accurately.
Here, in the conventional technology mentioned above, the use of two sensor units with different detection areas may increase the likelihood of achieving accurate detection of presence/absence of a human. However, the conventional technology mentioned above does not provide a procedure, method, or technique that enables recognition of whether a human is moving toward the spot where the sensor is provided or is crossing the detection area of the sensor with an accurate distinction. Thus, the conventional technology mentioned above is not free from the problem discussed above.